Various concepts for the avoidance of other aircraft, terrain, obstacles, and restricted areas have been discussed for a number of years. Some of these concepts include methods of assisted recovery or auto recovery from unusual flight situations. Still others create new and unique control systems or modes for existing control systems. However, few of these concepts have been implemented because of the technical challenges associated with flexibly coupling the autoflight systems (“AFS”) to emergency warning/alerting systems (“Emergency Systems”). Examples of Emergency Systems include traffic collision avoidance systems (TCAS), wind shear detectors, and Enhanced Ground Proximity Systems (EGPWS). Examples of AFS include a flight director (FD), an autothrottle (AT) and an autopilot (AP) system.
One challenge in coupling Emergency Systems to an AFS is that most Emergency Systems today generate only a simple signal set that enunciates various undesirable conditions. The lack of signal sophistication can make it difficult to drive an AFS response to perform a comprehensive auto-avoidance maneuver. Another challenge is that avoidance maneuvers directed by different Emergency Systems can vary for a given warning. The context and the degree of definition for a given maneuver may vary as well.
Additionally, many standard AFS may not be equipped with means for receiving different types of signals and requests generated by the various deployed Emergency Systems. AFS are presently designed to accept commands via a mode control panel (MCP), a guidance panel (GP) or from a Flight Management System (FMS). The flight crew uses the MCP/GP/FMS to manually activate various conventional AFS modes pre-programmed into the AFS and to manually establish targets (i.e. reference values) for those modes. Similarly, the FMS activates pre-programmed AFS navigation modes within the AFS and establishes targets or references for those navigation modes.
The existing set of deployed AFS modes is large and expanding. A single commercial aircraft autopilot may have upwards of 25 thrust, lateral and vertical maneuvering modes. The pilot's increasingly burdensome task is to remember and correctly apply the rules for each AFS maneuvering mode to the flight situation in which he finds himself A standard reference explaining AFS mode descriptions and AFS operation is RTCA DO-325 Minimum Operation Performance Standards (MOPS) for Automatic Flight Guidance and Control Systems and Equipment.
FIG. 1 is a simplified functional block diagram of a typical AFS 290 (i.e. an autopilot). Conventionally, mode selection and reference value setting is accomplished by the pilot 110 or by the FMS 111 via the MCP/GP 5. AFS mode selection determines which mode is initiated in the outer loop control sub-system 2 and which input from the aircraft sensors 4 are used for control feedback. The output from the outer loop control sub-system 2 controls the actual aircraft engine and control surface actuation 4 via the inner loop control sub-system 3. However, an AFS system 290 is currently not designed to receive mode input directly from Emergency Systems 100.
One solution to this problem entails creating one or more custom, pre-programmed AFS modes for a particular Emergency System that may be added to the list of outer loop modes. This approach has been used by Airbus SAS (headquartered in Toulouse, France) as explained in the Airbus documents “A New Step Towards Safety Improvement” and “Airbus New Autopilot/Flight Director TCAS Mode Enhancing Flight Safety During TCAS Maneuvers.” However, this approach adds to the growing inventory of AFS modes required to be learned by the pilot and is limited to only the new modes customized for this purpose. Generic legacy modes still cannot be manipulated to implement maneuvers based on an alert from an Emergency System.
FIG. 2 is a simplified functional block diagram illustrating a conventional information flow that occurs in a conventional cockpit environment. Typically, all data inputs have been funneled through the pilot 110 to be acted upon by manually manipulating the aircraft flight and engine controls 150. The pilot utilizes these real-time data inputs from the Emergency Systems 100 as well as other information resources 140 such as visual acquisition, air traffic control communication, and the Airplane Flight Manual to aid in development of his response.
As is well known in the art, a TCAS 120 renders threat detection information to the pilot 110 both visually via a traffic display device 122 and aurally via aural alerts 124. A threat resolution advisory (RA) (i.e. an alert) is then provided to the pilot 110 via a threat resolution advisory display 126 (see FIG. 1) to instruct the pilot how to avoid the threat. The TCAS RA provides information that identifies the type of vertical maneuver to perform (e.g., “CLIMB,” “DESCEND,” “MAINTAIN,” “ADJUST, etc.) and a vertical speed target value to either “fly to” or “avoid” depending on the type of vertical maneuver. Changes in the longitudinal and lateral axes are typically restricted, unless the changes are required to achieve the required vertical performance. The pilot 110 then makes a decision as to how to respond to the alerts received from the TCAS 120. The pilot may choose to ignore the alerts or to take action recommended by the threat RA or the aural alerts. Operation of an exemplary TCAS 120 is described in RTCA DO-185B entitled “Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance System II (TCAS II).”
Similarly, the EGPWS 130 provides ground proximity warnings visually via a terrain display 132 and audibly via aural alerts 134. In either case, an EGPWS simply generates a single, discrete electrical signal that indicates a pull up maneuver is required. No further guidance is provided to the pilot 110 by the EGPWS 130 for a pull up maneuver that reflects what is typically included in Airplane Flight Manuals, such as: a) apply maximum thrust, b) roll wings level, and c) increase pitch attitude and climb at best available angle. The pilot may choose to ignore the alerts or to take action indicated by the alerts.
Accordingly, it is desirable to provide systems and methods for translating an alert received from the Emergency System 100 into an AFS maneuver. In addition, it is desirable to provide systems and methods for coupling Emergency Systems to an AFS using existing AFS modes. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background. Although today's sophisticated aircraft include other types of information sources 140 that may produce alerts, the following disclosure describes only a TCAS 120 and an EGPWS 130 for the sake of brevity and clarity.